A crosspoint switch may be used to dynamically connect any one of a number of input channels to any one or more of a number of output channels. The crosspoint switch may be a single integrated circuit chip having an array of input ports and an array of output ports. For example, there may be 68 input ports and 68 output ports. Each output port has a dedicated multiplexer which is linked to all of the input ports, so that an incoming signal at an input port can be routed to a selected output port, a group of selected output ports, or all of the output ports. The routing of the signals by the crosspoint switch multiplexers is controlled by operations of address registers. In the example in which there are 68 input ports, the crosspoint switch will have 68 address registers or register pairs, since there is an address register dedicated to each multiplexer.
In order to increase the routing capability of a system, a printed circuit board may include an array of integrated circuit chips that house identical crosspoint switches. Thus, one of the chips may have its output ports connected to input ports of a second-stage crosspoint switch. The number of stages will depend upon the needs of the system supported by the crosspoint switches.
One concern in the routing of signals using wired transmission lines or conductive traces along a printed circuit board is that the signals will encounter “skin loss,” which is defined herein as the attenuation of high frequency components as a signal travels along a transmission path. That is, the low frequency components of a signal are transmitted more efficiently than the high frequency components of the same signal. The effects of skin loss vary as a function of the type of transmission medium (e.g., a copper trace along a printed circuit board), the length of the transmission path, and other properties (such as the width of the transmission path). Consequently, skin loss varies among different transmission paths. If the effects of skin loss are significant, signal integrity is jeopardized.
What is needed is an approach for effectively addressing skin loss and other signal losses that vary significantly on a channel-by-channel basis, so that the integrity of signals conducted via different channels of a system is preserved.